The overall goal of this project Is to understand the contribution of microtubules (MTs) to viral infectivity. MTs exist in dynamic and stabilized states. Upon stabilization, tubulin subunits comprising MTs become post- translationally modified (PTM). While both dynamic and stable MTs may play roles in viral infection, stable, PTM MTs may be particularly important. Viral proteins bind MT stabilizing factors, host cell factors critical for viral infectivity affect levels of stable MTs in cells and some viruses even enhance the formation of stable, PTM MTs in cell they infect. While we understand a number of the factors involved in MT stabilization pathways in cells, we have relatively little understanding of the relationship between viral infectivity and the functions that stable, PTM MTs provide during viral infection. In this project, we pursue three aims to enhance our understanding of the relationship between MT stability, tubulin PTMs and viral infectivity. We will conduct a screen for new factors involved in MT stability and viral infectivity by examining a family of MT interacting proteins implicated in MT stability. We will critically test the relationship between viral infectivity, tubulin PTMs, and MT stability, by developing strategies to generate cells lacking or overexpressing the two PTMs of tubulin that commonly occur in stable MTs of cells infected by viruses. And, we will examine the spatial relationships between viruses and different classes of MTs by developing new methods to image stable and PTM MTs in living ceils infected with fluorescent viruses and by testing the motility of viral motors on PTM MTs. These aims will be conducted in collaboration with the Goff, Naghavi, Walsh and Vallee groups. The results of these studies will provide new mechanistic information into how different classes of MTs contribute to viral infection and will provide new insights into how viruses manipulate and take advantage of host cell factors to augment their infection. These studies will also identify new host cell factors that influence viral infection and hence have important implications forthe development of anti-viral and viral- based gene targeting strategies.